Flexible container made of film material and filling method for filling such a container with a fluid substance

ABSTRACT

The application relates to a flexible container ( 3 ) made of film material for containing drinks, comprising a fin opening as well as film storage means which delimit a first compartment and a second compartment ( 17, 18, 19 ) of the container and which release a second compartment ( 18, 19 ) when a predetermined degree of filling of the first compartment ( 17 ) is reached. By means of the film storage means, which, for example, can be formed by folding the side strips ( 20, 21 ) double in the longitudinal direction and holding them in place with the aid of adhesive tape, adhesive or fusion welding of the film material, uniform filling of the first compartment can be obtained, the flexible container largely remaining out of contact with the walls of the surrounding outer container. When the first compartment ( 17 ) has been filled the film storage means are released by the increase in the fill pressure and the second compartment ( 18, 19 ) can be filled so that uniform contact of the flexible container with the wall of the outer, rigid container is obtained. Using the flexible container and using the filling method according to the present invention high fill rates can be achieved and stresses are prevented from becoming too high in certain sections of the flexible container.

The invention relates to a flexible container made of film material forcontaining a fluid substance comprising a fill opening and apartitioning means along which a first container wall part is placedagainst a second container wall part, the partitioning means dividingthe container in a first and a second compartment, and to a fillingmethod for filling such a container.

A flexible container for containing carbonated drinks, such as beer, isdisclosed in Netherlands Patent Application no. 1 009 654, filed on 15Jul. 1998 in the name of the Applicant. The known flexible container, orbag, is made of film material and is provided with a dispenser tubelocated between the front and back layers of film and a plastic fillercap connected to said dispenser tube. After the flexible container hasbeen introduced in the rolled-up state into a relatively rigid outercontainer, the drink, such as, for example, beer, can be introduced intothe flexible container via the filler cap. The flexible containerunfolds until it is in contact with the inside wall of the rigidcontainer. After filling, a dispensing line can be connected to thefiller cap by the user (consumer) and the drink can be dispensed fromthe bag by applying an overpressure within the rigid container.

To prevent the bag filled with drink being damaged during use ortransport it is important that when it is completely filled this bag isin close contact with the inside wall of the rigid container. It hasbeen found when filling the bag that, under the influence of gravity,the lowest parts of the bag fill more rapidly than other parts andbecome trapped prematurely in contact with the inside wall of the rigidcontainer. As a result the bag is not able to unfold in the desireduniform manner and high stresses can be generated. This can beproblematical in particular in the area where the bag is attached to thefiller cap if the bag is filled in the upright position, in which casethe highest point is formed by the filler cap. Furthermore, as a resultof the non-uniform unfolding of the bag, shut-off areas can form, as aresult of which the bag is not completely filled.

From WO97/34794 a flexible container according to the preamble of claim1 is known in which a controlled unfolding of the flexible innercontainer and complete filling of the rigid outer container by the innerflexible bag is achieved by use of sealing of two corner parts forminglugs which upon filling conform to the parallellepipedum-shaped rigidouter container. In addition, especial folding pattern using atube-shaped cover, which slights of the folded inner container uponfiling causes a gradual unfolding and proper filling of theparallellepipedum-shaped outer container. By permanently sealing ofparts of the flexible inner container, useful container material islost. Furthermore, a very complex folding pattern is required includingadditional sleeve material for proper unfolding of the known flexibleinner container.

It is therefore an aim of the present invention to provide a flexiblecontainer or bag and a method for the filling thereof with which uniformfilling is possible without parts of the bag prematurely becomingtrapped between the walls of the rigid outer container.

A further aim of the present invention is to provide a bag with which ahigh fill rate can be achieved and with which it can be easilyestablished while filling whether the filling process meetspredetermined quality requirements.

To this end the flexible container according to the invention ischaracterised in that the partitioning means comprises a restrainingmember which maintains a substantially fluid tight separation of thefirst and second compartment until a predetermined pressure is achievedin the first compartment, at which predetermined pressure therestraining member is released by the fill pressure for placing thefirst and second compartment in fluid communication.

As a result of dividing the flexible container into sub-compartments itis possible to achieve successive controlled and localised filling ofeach compartment and, consequently, uniform film distribution. With thisarrangement the shape which the bag assumes during filling is no longerdetermined exclusively by gravity. After the first compartment, that,for example, can comprise a central cylindrical volume, has been filled,a pressure is built up therein such that the film storage means arereleased. As a result the access to the second compartment is opened up,so that this compartment is then able to fill with drink. It has beenfound that using the bag according to the present invention uniformfilling of the bag can be obtained at high fill rates, whilst at thesame time uniform contact of the filled bag with the wall of the rigid,outer container can be obtained. As a result the bag is adequatelysupported during use and transport and the risk of damage is reduced.

In this application “fluid substance” means a substance with which acertain degree of flow is possible, such as a fluid, a paste or agranulate. The fluid can comprise a drink, for example a carbonateddrink, such as beer. In this case a pressure of approximately 1 barprevails in the bag during filling and a pressure of approximately 2 barprevails in the rigid container. The paste can be a food product, suchas tomato puree, or any other paste.

According to one variant of the present invention the restraining membercan be formed by closure lines in the film material, such as, forexample, fold lines or join lines along which the front and back filmlayers of the bag are joined to one another. According to anothervariant the restraining member is acting on a part of the container thathas been tucked inside itself from an upper end or lower end or from thelongitudinal edges.

In one embodiment which is to be preferred the restraining membercomprise closure lines which essentially extend from the top to thebottom of the container, along which closure lines a front film layer ofthe container is essentially sealed in contact with the back film layerof the container. The closure lines can be formed by gluing or sealingthe film layers, but are preferably formed in that the container hasbeen folded double along the closure lines, a first layer of the filmmaterial folded double being attached via means offering resistance to asecond layer of the film material folded double. The means offeringresistance can be formed by adhesive between the folded film layers,sealing of the film layers or by adhesive tape. During filling the meansoffering resistance give way and controlled unfolding of the bag takesplace, without contact with the wall and without accumulation of thefluid substance in the lower part of the bag, so that a uniformdistribution of the film over the wall of the outer, rigid containerwill be obtained.

As a result of the controlled unfolding of the flexible container, notonly are high fill rates (12 liters per minute or higher) obtained whenfilling the flexible container, but it is also possible to sample thefill pressure and/or flow rate during filling, for example with the aidof a computer, the fill pressure and/or flow rate changing when onesub-compartment unfolds. By detecting a change in the fill pressureand/or flow rate it can be ascertained with certainty that allsub-compartments of the flexible container have unfolded, this enablingsimple quality monitoring.

A few embodiments of a flexible container and a filling method accordingto the present invention will be explained in more detail with referenceto the appended drawing. In the drawing:

FIG. 1 shows a longitudinal section of a bag according to the presentinvention provided with a filler cap, accommodated in a relatively rigidouter container;

FIG. 2 shows a detail of the filler cap attached to the bag during thefilling process;

FIGS. 3–6 show various stages in the folding of a bag according to theinvention;

FIGS. 7 and 8 show side views of two alternative embodiments ofrestraining members according to the present invention incorporatingfolding, respectively, an upper end and a lower end of the bag inwards;

FIG. 9 shows a diagrammatic plan view of a restraining memberincorporating folding the longitudinal sides of the bag inwards; and

FIG. 10 shows a graph of the flow rate of the fluid (beer) when filling.

FIG. 1 shows an assembly 1 of a relatively rigid outer container 2 witha flexible container, or bag, 3 accommodated therein. The bag 3 is fixedin a sealed manner at an upper end to a fixing lip 4 which forms part ofa plastic filler cap 5. The filler cap 5 is attached to a neck 7 of therigid outer container 2 via an annular shoulder 6 such that it isclamped. The filler cap 5 is further connected to a dispenser tube 8which extends into the flexible bag 3 to prevent the front and backwalls coming into contact with one another. A fill opening 9 in thefiller cap 5 is closed off. The fill opening 9 is made in the end of ashut-off valve 10 resiliently accommodated in the filler cap 5. The fillopening 9 is exposed by placing a filler tube 12 from a fillinginstallation on the shut-off valve 10 and pushing the latter downwards,as is shown in FIG. 2.

FIG. 2 shows an enlarged view of the filler cap 5 of the flexible bag 3and shows how fluid can be introduced into the bag 3 via the filler tube12 by pushing down the shut-off valve 10. During this operation air isable to escape from the space located between the bag 3 and the outercontainer 2 via ventilation passage 12′ in filler tube 12. Furthermore,an internal pressure of, for example, 2 bar can be applied in the outercontainer 2 via the vent opening 12′, for a fill pressure in the bag 3of approximately 1 bar if the fluid is beer. In the filled statevirtually the entire outer surface of the bag 3 is in contact with thewall of the outer container 2.

A recording device for measuring the flow rate and/or the pressure inthe filler tube 12 is shown diagrammatically by 11. The device 11 can bea flow sensor or pressure sensor which is connected to a personalcomputer.

To prevent some parts of the bag 3 prematurely becoming trapped inengagement with the wall of the outer container 2 during filling, a foldpattern has been made in the bag in the embodiment according to FIGS. 3to 6.

FIG. 3 shows a side view of the bag 3 in its flat state, in which stateair has been removed from the bag via the filler cap 5 and the dispensertube 8 so that the bag is completely flat. The bag 3 has been made froma multilayer film which, for example, comprises an aluminium-polyethenelaminate with a thickness of approximately 70 μm to 100 μm. In theembodiment according to FIG. 3 four fold lines 13, 14, 15 and 16 areindicated, along which the film material is folded. A first centralcompartment 17 of the bag 3 and two side compartments 18, 19 are formedby the vertical fold lines 13 and 14. By folding the side strips 20, 21over along the fold lines 13, 14, sealing lines are formed along thefold lines 13, 14, so that the fluid introduced into the centralcompartment 17 through the filler cap 5 is not able to enter the sidecompartments 18, 19. As shown in FIG. 4, the folded-over side strips 20,21 are held in place by adhesive tapes 23, 24 applied along the freeedges thereof. The bottom section 25 in FIG. 4 is then folded backwardsout of the plane of the drawing along the fold line 15, against the midsection 26. In FIG. 5 the mid section 26 is folded forwards out of theplane of the drawing along the fold line 16, against the top section 27,so that the configuration according to FIG. 6 is obtained. The bag 3folded in accordance with FIG. 6 is rolled up so that it can beintroduced through the neck 7 of the outer container 2. A filler tube 12is then connected to the filler cap 5 and the bag 3 unfolds duringfilling, first in the longitudinal direction to give the configurationwhich is shown in FIG. 4. The central compartment 17 is then first ofall filled with fluid from the bottom up to the dispenser tube 8, theside strips 20, 21, which are held in place by the adhesive tapes 23,24, being prevented from engaging on the wall of the outer container 2.After the central compartment 17 has been filled and the film has beendistributed in the longitudinal direction over the entire height of theouter container, the pressure therein will rise up to a value at whichthe adhesive tapes 23, 24 detach or tear, so that the compartments 18and 19 are released and are then able to fill with fluid.

In this way relatively high fill rates, such as, for example, 12 litersper minute, can be obtained and a uniform increase in volume of the bag3 is achieved without stresses becoming too high, in particular on thefixing lip 4 of the filler cap 5. What is achieved by means of theuniform filling of the bag 3 in accordance with the method describedabove is that the bag 3 comes uniformly into contact with the outercontainer 2, so that the bag 3 is adequately supported when filled andis protected against damage.

For thicker films, which because of their stiffness unfold under higherpressures, the adhesive strength of the adhesive tapes 23, 24 has to behigher and stronger adhesive tapes have to be used.

Alternative film storage means for forming different compartments 17, 18and 19 in accordance with FIGS. 3 to 6 will be obvious to those skilledin the art. For instance, the adhesive tapes 23, 24 can, for example, bereplaced by adhesive or fusion welding of the film material. It is alsopossible to fuse the front and back layers of film material of the bag 3to one another in the flat state, as shown in FIG. 3, along interruptedor uninterrupted vertical lines 13, 14 with a strength such that whenthe central compartment 17 has been filled the fusion seals 13, 14 giveway under the pressure and release the side compartments 18, 19.

It is also possible to provide the bag with elastic in the transversedirection or to place the bag in an elastic jacket or sleeve.

Alternative embodiments of film storage means for uniform unfolding of abag 30 having a filler cap 31 are shown in FIGS. 7 and 8. In this casethe upper and the lower section 32, respectively, of the bag 30 has beenturned “inside out” so that the section 32 is located between a frontand back layer of film material of the top or bottom compartment 33. InFIG. 7 the upper compartment 32 will be expelled upwards on filling,after which the lower compartment 33 is filled. In FIG. 8 the uppercompartment 33 will be filled first when filling the bag 30, afterwhich, when a predetemmined fill pressure is reached, the lowercompartment 32 will be expelled downwards until the lower compartment 32has also filled.

FIG. 9 shows a further alternative embodiment where the material of thebag 34 has been displaced from the side edges 36, 37 indicated by abroken line towards the centre line, so that side compartments 42, 43and a central compartment 38 are obtained. The side compartments can befixed in the folded position by glue points 40, 41. Depending on theflexibility of the bag 34, the glue points 40, 41 can also be omitted.After filling the central compartment 38 the parts 36, 37 folded doublewill be expelled outwards and the bag 34 will achieve the filledconfiguration.

In the case of the examples described above the bag 30, 34 has alwaysbeen placed upright so that the filler cap 31, 38 forms the highestpoint. It is also possible to fill the bag according to the presentinvention in the upside-down position, so that the filler cap 31, 38forms the lowest point, the same advantages as have been discussed abovebeing obtained.

FIG. 10, finally, shows a graph of a flow rate determined using thedevice according to FIG. 2 against time when filling a bag of 4 literscapacity with beer, the fill pressure being 1 bar and the pressureinside the rigid container being 2 bar. The bag was folded in accordancewith the pattern that is shown in FIGS. 3 to 6. On filling the centralcompartment 17 the flow rate, after having been essentially constant,decreases sharply to point A, after which the flow rate suddenlyincreases. This means that one of the adhesive tapes 23, 24 has detachedand one of the side compartments 18 or 19 has been released. The secondcompartment is released at point B in the graph according to FIG. 10,after which the filling process is completed relatively quickly. In thecase of a perfectly symmetrical configuration of the compartments,points A and B will be coincident. By detecting the point in time atwhich the side compartment unfolds by determining the pulse-like changesin the flow rate according to FIG. 10 it is possible to determine thatthe side compartments have unfolded and that, on the basis of this, thefilling process has proceeded in accordance with specifications.

1. Filling method for filling a flexible container with a fluidsubstance, comprising the following steps: placing the flexiblecontainer in a relatively rigid container, the flexible container beingprovided with a film material for containing a fluid substancecomprising a fill opening and a partitioning means along the which afirst container wall part is placed against a second container wallpart, the partitioning means dividing the container in a first andsecond compartment, characterised in that the partitioning meanscomprises a restraining member which maintains a substantially fluidtight separation of the first and second compartment until apredetermined pressure is achieved in the first compartment, wherein atthe predetermined pressure, the restraining member is released by thefill pressure for placing the first and second compartment in fluidcommunication; filling the first compartment with the fluid substancevia a fill opening in the container, activating the film storage meansvia the fill pressure such that the second compartment is released, andfilling the second compartment until the film material of the flexiblecontainer is at least largely in contact with the wall of the rigidcontainer; wherein, during filling, at least one of a flow rate and afill pressure is measured and a change in the at least one of the flowrate and the fill pressure is determined on activation of the filmstorage means.
 2. Method according to claim 1, characterised in that airis removed from the flexible container before the flexible container isinserted in the rigid container.
 3. Method according to claim 1,characterised in that the flexible container is folded double alongclosure lines, the container sections folded double being attached toone another by the restraining member which can be released by fillpressure.
 4. The method according to claim 1, further comprisinginserting said flexible container into a generally cylindrical, rigidouter container; wherein a central cylindrical area is defined betweenthe closure lines; wherein upon filling and expanding the flexiblecontainer, vertical sides of the flexible container outside the closurelines do not press against the walls of the rigid outer container; andwherein after release of the closure lines, the flexible containermaterial outside the closure lines is pressed into contact with therigid outer container.